Abstract
Introduction: Gold nanoparticles have been used as radiation dose enhancing materials in
recent investigations. In the current study, dose enhancement effect of gold nanoparticles
on tumor cells was evaluated using Monte Carlo (MC) simulation. Methods: We used
MCNPX code for MC modeling in the current study. A water phantom and a tumor region
with a size of 1×1×1 cm3 loaded with gold nanoparticles were simulated. The macroscopic
dose enhancement factor was calculated for gold nanoparticles with sizes of 30, 50, and
100 nm. Also, we simulated different photon beams including mono-energetic beams (50-
120 keV), a Cobalt-60 beam, 6 & 18 MV photon beams of a conventional linear
accelerator. Results: We found a dose enhancement factor (DEF) of from 1.4 to 3.7 for
monoenergetic kilovoltage beams, while the DEFs for megavoltage beams were negligible
and less than 3% for all GNP sizes and concentrations. The optimum energy for higher
DEF was found to be the 90 keV monoenergetic beam. The effect of GNP size was not
considerable, but the GNP concentration had a substantial impact on achieved DEF in
GNP-based radiation therapy. Conclusion: The results were in close agreement with some
previous studies considering the effect of photon energy and GNP concentration on
observed DEF. Application of GNP-based radiation therapy using kilovoltage beams is
recommended.